Industrial oven



P 1962 B. J. FALANGA ETAL 3,052,040

INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 1 Sept. 4, 1962 .B.J. FALANGA ETAL 3,052,040

INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 2 E JF'gL, HNE'HEEE'E' QQ/SH 5 -43 E M/g5 Sept. 4, 1962 B. J. FALANGA ETAL 3,052,040

INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 3 Sept. 4, 1962 B. J.FALANGA ETAL 3,052,040

I INDUSTRIAL OVEN Filed June 11, 1959 4 Sheets-Sheet 4 United 4.

3,052,040 INDUS OVEN Bruno J. Falanga, Lawrence, and Grenville B.Gerrish,

M elrose, Mass; said Falanga assignor to Western Electrrc Company,Incorporated, New York, N .Y., a corporation of New York Filed June 11,1959, Ser. No. 819,772 2 Claims. (Cl. 34202) This invention relates toovens, particularly industrial ovens, for heat treating materials atcontrolled elevated temperatures.

Various materials to be conditioned for use must be subjected tocontrolled elevated temperatures. When such treatments involvepyrolizing processes, toxic gases may 'be generated presenting theproblem of removing the gases from the treating area while maintainingthe area at the desired temperature.

The object of the present invention is an oven which, although simple instructure, is highly efiicient in providing a solution to this problem.

In accordance with the object, the invention comprises an oven having amaterial treating chamber mounted within a heated air circulating systemwhich transfers heat through the chamber Wall to the heat treating areawithout contaminating the air so that it may be recirculated repeatedlythrough the heater. A portion of the heated circulating air is divertedto and through the chamber to an exhaust outlet to supply heat directlyto the articles being treated and to carry away the toxic or otherobjectionable gases generated in the process.

In one oven, according to the invention, which is particularly adaptedfor pyrolizing anodes for tantalum capacitors, the treating chamber isan elongated tubular structure of heat conducting material closed at itsends and provided with a longitudinal opening for admitting articles tobe treated. If desired, a cooling jacket may surround this opening toprotect portions of the article from the heat of the chamber. A hot aircirculating system with rows of inlet and outlet apertures in thetreating chamber, as well as in the intermediate chamber whichsubstantially surrounds the treating chamber, causes a continuous flowof hot air around the outside surface of the treating chamber tomaintain it at the desired temperature.

Other ducts, connecting the heating chamber with the circulating systemand with an exhaust, divert some of the heated air into the chamberwhere it transfers heat directly to the articles and produces suificientpressure to force out the generated gases. By proper regulation of theheater and control of the proportion of the air recirculated, the ovenmay be operated at high efliciency by minimizing the heat lost throughthe exhaust.

Other objects and advantages will be apparent from the followingdetailed description when considered in conjunction with theaccompanying drawings wherein:

FIG. 1 is a vertical sectional view of the oven taken near the back ofthe oven;

FIG. 2 is a vertical sectional view taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of the portion of theoven including the treating chamber and the adjacent structure; and

FIG. 4 is an enlarged fragmentary isometric view of the oven structure.

The oven includes a base 10 supported on rollers 11. A main housing 12mounted on the base 10 has a blower or fan 14 mounted therein. A shaft15 of the fan '14 is journalled in suitable bearings 16 and has a pulley17 mounted on its outer end. A motor 18 mounted on the base 10 has apulley 19 mounted on its shaft 20 and connected to the pulley 17 by abelt 21. The circulating system, including the fan, has a tubular member22 extending from an inlet 23 of the fan 14 to a vertical hollow portion24.

A hollow receptacle 26 disposed in registration with an aperture 27 inthe back Wall of the main housing 12, receives suitable filters 28. Theaperture 27 is a makeup air inlet for the circulating system, the airpassing through the filters 28 and through a tubular passageway 29 intothe tubular member 22. The circulating system for the oven also includesa tubular member 31 extending from the outlet end 32 of the fan upwardlyand then horizontally at 33 where it connects with a vertical portion34, aligned with the portion 24, and with a portion 35. The portion 35is separated for a portion of its length from the portion 33 by apartition 35, at the right end of which the portion 35 joins the portion33 and the portion 34. The right one-third of the portion 33 and itsconnection with the vertical portion 34 may be defined as a by-pass 33'for a reason hereinafter described. A damper 36 pivotally supported at37 is disposed in the horizontal portion 33 at the exit end of theby-pass 33'.

The circulating system and substantially all of the structure within themain housing 12 is surrounded with a suitable insulating material 38.For the purpose of illustration only, FIG. 2 is shown with a portion ofthis insulating material removed in the area between tubular member 31,extending upwardly from the outlet 32 of the fan, and the recirculatingportions 24- and 34 to illustrate in FIG. 2 the contours of the portionsand a heating chamber 39 disposed therebetween.

The heating chamber 39 is widened to provide an in terior which,although substantially equal in depth is larger in cross-sectional areathan the cross-sectional area of the tubular member 31 to allow the airto remain in the heating chamber a suflicient length of time, or to movetherethrough at a greatly reduced rate of speed, to heat the air to thedesired temperature, such as a maximum temperature of 1,000 F. Theheating chamber 39 may be heated in any suitable manner such as by oneor more heating coils 40. Furthermore, the areas or portions 24 and 34are flared outwardly, respectively, to correspond with the width of theheating chamber 39 to allow the recirculated air to spread out and fillthe heating chamber. The portion 24 retards movement of the large bodyof air leaving the heating unit and starting its next circuit.

With reference to FIG. 1, the arrows illustrate the travel of the heatedair upon leaving the fan through a thermal coil 41 into an inlet 42 andout of an outlet 43. The thermal coil 41 is of a commercially known typeconnected to a variable control unit 44. The inlet 42 is connected tothe portion 33 in advance of the damper 36 at the by-pass 33' and theoutlet 43 is connected to the portion 35 as shown in FIGS. '1 and 2. Thedamper 36 disposed at the entrance end of the by-pass 33 controls thepercentage of heated air directed through the inlet 42. If the damper isopen wide or horizontal, almost all the air will be recirculated throughthe by-pass 33' with almost none of the air entering the inlet 42,whereas if the damper is closed (vertical) all of the air will be causedto move through the inlet '42. The unit 44 is also of a commerciallyknown type and when set, it is adapted to maintain a predeterminedselectively variable temperature in the heating chamber. The thermalcoil 41 aiiected by the temperature changes in the vertical member 31causes the unit 44 to close one or more circuits through the heatingcoils 40 when the temperature in the system, including the heatingchamber, drops below a given value and holds the circuits closed untilthe temperature returns to the given value. The unit 44 is adjustablyset to the desired given temperature. The circuits are represented by acable 68, portions of which are shown in FIGS. 1 and 2.

The inlet 42 and the outlet 43 are shown in FIG. 3. In this figure itappears that the inlet 42 and the outlet 43- are vertically aligned butthey are disposed in staggered relation as illustrated in FIG. 1.

FIGURE 3 illustrates a treating chamber 45 which is of sufficient lengthas somewhat illustrated in FIG. 4, to receive 32 articles 46 disposedupon leads 47 extending outwardly from their mountings 48 which arecarried temporarily by a holder 49. The treating chamber 45 is formed ofheat conducting material, such as stainless steel, and is closed at bothends but has a longitudinal opening 50 for receiving the row of spacedarticles or material 46 to be treated. An intermediate or circulatingchamber 51 surrounds the major portion of the treating chamber 45 and isdisposed in between outer chambers 52 and 53. Walls 54 of thecirculating intermediate chamber, formed of simiiar heat conductivematerial, extend the full length of the treating chamber 45 and theouter chambers 52 and 53 so as to be closed by the ends which close thetreating chamber 45 and outer chambers 52 and 53.

Longitudinal rows of apertures 55 in the bottom wall 54 of theintermediate chamber 51 serve as inlet ducts for forced air coming intothe outer chamber 52 from the inlet 42. Other rows of apertures 56 inthe upper wall 54 of the intermediate chamber 51 serve as outlet ductsfor the air passing from the circulating intermediate chamber throughthe outer chamber 53 and through the outlet 43. The inlet ducts 55 andthe outlet ducts 56 cause the circulating chamber 51 to be an airpassageway which is under the control of the damper 36. The damper 36 isdisposed in the system downstream of the inlet 42 and the inlet ducts 55adjacent the entrance end of the by-pass 33. Therefore, the angularposition of the damper 36 controls the flow of heated air through thecirculating chamber 51 and about and through the treating chamber 45 viathe apertures 55, 57, and 59.

A row of apertures or bypassing ducts 57 allow a percentage of theheated air to be forced to travel through a vertical passageway orfeeding line 58 and through spaced rows of inlet ducts 59 to enter thetreating chamber 45. The inlet ducts 59 are staggered or disposed in tworows, as illustrated in FIG. 4, but both rows are positioned back of abaflie-plate 60 so that all air entering the treating chamber will bedirected away from the article or material46. Rows of exhaust or outletducts 61, which are larger than the inlet ducts 59, permit air and gasesmixed therewith to pass from the treating chamber 45 through an exhaustline 62. The inlet ducts 59, in the present instance, are substantiallyone-half the diameter of the outlet ducts 61.

A cooling jacket or shield 63 has an elongated aperture 64 thereinthrough which the articles 46 on their leads 47 and their supports 48may extend, to protect the supports against the heat of the treatingchamber and cool the air escaping from the treating chamber. The

holder 49 with the supports 48 therein closes the opening 50. Thecooling jacket 63 is hollow as at 65 for the circulation of coolant suchas water through an inlet 66 from a supply, not shown, through thecooling jacket 63 and through an outlet 67 back to the supply.

Operation The oven may be readied for operation in advance of theinsertion of the material or articles to be treated by energizing theheating coils 40 to bring the temperature in the heating unit 39 to thatdesired. The unit 44 is set to maintain the temperature in advance ofthe treating chamber 45 at a given level. The motor 18 may be energizedand the group of articles 46 in their holder 49 may be inserted in theoven to locate the portions to be treated in the treating chamber 45.

The articles will remain in the heating chamber a predetermined lengthof time during which there is a continuous recirculation of air at apredetermined elevated temperature through the oven. A predeterminedportion of this circulating air is directed into the treating chamber ina path directed away from the articles but caused to fill the treatingchamber to cause an internal heating of the chamber through a continuouspassing of air through the chamber.

An important purpose of this small percentage of the total air,circulated and recirculated, which in the present instance is 30%, is toremove gases resulting from the treatment of the materials from thetreating chamber. At the same time, the major portion of the heated airis recirculated in such a manner that it is caused to flow about theheat conducting material of the treating chamber, applying an externalheat to the treating chamber constantly to retain the predeterminedtemperature within the treating chamber. The recirculated portion, or inthe present instance, the 70% of the heated air is recirculated throughthe heating unit where it is reheated, for example, to a temperature inexcess of that required for the treating chamber, so that the pulling inof an additional 30% of air at room temperature through the filters 28and mixed with the super heated recirculating air, will result in airflowing into and around the treating chamber at a temperature desiredfor treating the material or articles 46.

The temperature of the air is controlled through the unit 44 and thepercentage of recirculation of the air is controlled partially throughthe sizes of the apertures 59 and 61 and also by the damper 36.

It is to be understood that the above described arrangements are simplyillustrative of the application of the principles of the invention.Numerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

1. An oven for heat treating a material, carried by a support of a givensize which material expels a gas when subjected to a predeterminedtemperature comprising a treating chamber substantially circular incrosssection and having a material receiving opening adapted to beclosed by the support for the material, the treating chamber beingformed of heat conducting material and having an inlet duct adjacent oneside of the opening and an outlet duct 'adjacent the opposing side ofthe opening, an air circulating system including a circulating chamberdefining an air passage partially surrounding the treating chamber andhaving inlet and outlet openings disposed at opposing sides of thetreating chamber so that heated air passing through the circulatingchamber from the inlet to the outlet openings will have to move aboutand externally heat the treating chamber, a feeding line open to theinlet duot, an exhaust line open from the outlet duct to the atmosphere,a by-passing duct connected to the feeding line to direct 'a givenpercentage of the heated air through the inlet duct into and through thetreating chamber to internally heat the treating chamber and causeexhausting of gases expelled from the material to pass through theoutlet duct and the exhaust line, an air heating unit in the aircirculating system to heat the air therein to a predetermined elevatedtemperature, and means to cause the heated air to flow continuouslythrough the system with :a given percentage of the heated air to flowthrough the circulating chamber to externally heat the treating chamberand the remaining percentage of the heated air to flow through the bypassing duct.

2. An even according to claim 1 in which a bafile is mounted adjacentthe opening in the treating chamber and extends between the inlet ductand the material to deflect the heated air away from the material andcause it to circulate through the treating chamber in a path away from:the material to the outlet duct.

References Cited in the file of this patent UNITED STATES PATENTS1,902,575 Nichols Mar. 21, 1933 2,029,117 Otis Jan. 28, 1936 2,365,890McBean Dec. 26, 1944 2,627,838 Huggins Feb. 10, 1953 FOREIGN PATENTS461,813 Italy Feb. 15, 1951 1,063,054 France Apr. 29, 1954

